The present invention relates to a device for positioning a tool or instrument in a duct and recovering it by causing a vector fluid to flow, usable more particularly for working self contained hydraulic pumps at the bottom of wells, in production through the inside of production tubing.
The invention relates particularly to positioning and recovering self contained tools at the bottom of water or hydrocarbon producing wells.
This technique is more particularly interesting in the case of independent well bottom hydraulic pumps, and in particular, hydraulic pumps of the jet pump type, when the production is brought to the surface by production tubing. It is the example which has been chosen here for describing the invention, but is also applies to all equipment which may be useful for carrying out tests, regulations, measurements and for safety purposes at the bottom of the wells in particular pressure, temperature of flow rate recorders which can be operated in this way, alone or associated with self contained pumps.
The invention also applies to gas producing wells and to wells activated by gas-lift.
Hydraulic well bottom pumping assemblies and, particularly, jet pumps are relatively compact. Their weight and size are sufficiently reduced to allow them generally to be installed and moved inside a production tubing. These pumps are very often simply placed on a receptacle from which they may be readily separated. They may then be considered as free, for they may be rapidly placed in position or removed from the well by a hydraulic flow or by wire-line working. With respect to the other non free activation systems (rod pump, conventional electric pumps), maintenance thereof is therefore simpler, more rapid and less expensive.
The technique the most generally used consists of feeding the free hydraulic pumps with a drive fluid injected in the production tubing. The production is then raised through the annular space between this production tubing and the casing. In some cases, raising the production may take place through another production tubing, if a double completion is provided.
In the case of production through the annular space, the drive pressure in the production tubing allows the pump to be applied and maintained in its housing at the bottom of the well. To raise the pump, the flow of the fluids is reversed. A valve placed at the delivery side of the pump allows the pressure necessary for its movement to be maintained downstream thereof.
Production through the annular space presents risks in the following situations, which occur relatively frequently: namely, corrosive fluids (crude and water from the field), in particular when they contain sulphurated hydrogen or carbonic gas, abrasive fluids, when production takes along with it sand from the formation, and fluids which form paraffin, asphalt or salt deposits. The production of such fluids may cause damage to the tubes, namely, production tubing and casing, and a clogging of the annular space.
Moreover, the geometry of the annular space is not well defined, and the production tubing being positioned in an irregular manner does not allow the flow of fluids produced to be readily calculated whereby deposits are formed in the zones of lower flow rates and, in particular, at the contact points between the production tubing and the casing.
The present invention overcomes these disadvantages by allowing production through the production tubing. With this method, the drive fluid, which is preferably a fluid suitably treated to prevent risks of corrosion, abrasion and deposits, is injected into the annular space.
The pumped fluid mixed with the drive fluid, is raised to the surface through the inside of the production tubing where corrosion, erosion and deposit phenomena may be more readily controlled and treated.
Possible damage by the fluids produced is thus limited to the inside of the production tubing, which tubing is of a smaller diameter. The repairs which concern solely the production tubing and not the assembly of this tubing and the casing are therefore more rapidly executed and are less costly and the safety of the well better ensured in the case of a breakdown.
Conventional techniques may be applied for positioning and removing a well bottom hydraulic pump with production through the production tubing. Techniques using wire-line working and a pumped auxiliary tool have been proposed in the patent GB-A-No. 2 107 397 in relation with hydraulic jet pumps. However, these proposed techniques seem relatively time consuming to put into practice and require complementary tools.
Other prior art techniques of operating with fluid flow are illustrated, for example, by the patents U.S. Pat. Nos. 3,395,759, 3,543,852, 4,360,063, 3,229,785 and 3,789,925.
The essential purpose of the present invention is to provide a device for positioning a tool or an instrument in a duct and recovering it. It may be used, more particularly, for stimulating the production of an oil well by allowing a self contained hydraulic pump to be placed at the bottom of the well, with the pump may allow production through the inside of production tubing.
With the device of the invention, it will be possible to overcome the drawbacks of the prior art such as described in, for example, U.S. Pat. No. 3,530,935.